Sideboard



FIG. 1 is a front perspective view of a sideboard showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a side view, the opposite side being a mirror image thereof;and,

FIG. 4 is a top view thereof.

The broken lines showing the hardware is for illustrative purposes onlyand forms no part of the claimed design.

The ornamental design for a sideboard, as shown and described.